Safety device for reciprocating machines



F. JOHN.

SAFETY DEVICE FOR RECIPROCATING MACHINES.

APPLICATION FILED SEPT-18,1920.

WIT-u.

% fie eaves M M NITED PAENT OFFlfiE.

FERDINAND OHN, 0F ERKELEIIZ, RHINELAND, GERMANY.

SAFETY DEVICE FOR RECIPROGATING MACHINES.

,cating Machines, of which the following is a specification.

In machines which work at high power and great pressure, such as presses, powerhammers, shearing machines and the like, safety devices have already been provided for preventing breakage of parts of the machine, should the reciprocating parts meet with too great resistance. This may occur, for example, if a large obstruction becomes interposed between the table and the hammer of a press and the latter is unable to shape the article under its maximum pressure. In such case, the momentum of the fly wheel causes breakages or jamming of parts of the machine, thus rendering it inoperative for some considerable time.

Heretofore the safety devices have generally been of costly and complicated construction, in some cases only allowing a small margin of safety, and frequently absorbing part of the driving power of the machine.

According to the present invention, the safety device is of simple construction and comprises more particularly an eccentrically mounted driving member, retained in its normalworking position by a safety bolt, spring or the like adapted to come into operation, when the load becomes excessive, so as to cause movement of the eccentrically mounted driving member in such a manner as to prevent excessive stress on the parts of the machine. When the obstruction has been removed the driving member may be returned to its normal working position.

The improved safety device is illustrated on the drawings as applied to various reciprocating machines by way of example.

Figure 1 is a side view of a press, partly in section, with the parts in working position.

Fig. 2.shows the press of Fig. 1 in its inoperative position.

Figs. 3 and 4 are views corresponding to Figs. 1 and 2 showing the application of a spring instead of a safety bolt.

Figs. 5 and 6 are similar views of a. toggle Specification of Letters Patent.

Patented Mar. 1, 1921.

Application filed September 18, 1920. Serial No. 411,272.

press and Figs. 7 and 8 are corresponding views of a multiple toggle press.

Referring to Figs. 1 and 2, the table 1 supports the anvil 2 on which the shaping or pressing operation is effected by the hammer 3. The latter has a connecting rod 4 to a crank 5, the crank shaft 6 carrying the fly wheel 7. The crankshaft 6 is mounted eccentrically to an eccentric 8 rotatable in a journal 9 in the machine frame 11. The eccentric 8 carries a projecting arm 10 which is retained in normal position byv means of a fragile bolt 13 passed through a boss 12 on the frame 11.

If a force P acts upwardly on the rod 4, this force will act through a distance Z, so that the moment about the center of the eccentric 8 will be PXZ and the moment about the fragile bolt 13 will then be p L where p is the stress on the bolt 13, L the distance between the bolt 13 and the center of the eccentric 8 and Z the distance between the centers of the eccentric 8 and crankshaft 6.

If now, during operation of the press, an obstruction 14 (Fig. 2) becomes interposed between the anvil 2 and hammer 3 and exceeds a certain height, the momentum of the flywheel will cause fracture of the bolt 13 and consequently the arm 10 will turn, rotating the crankshaft 6 and, lifting it to a greater or less extent according to the dimensions of the object 14, as clearly seen in Fig. 2. When the obstruction 14 has been removed, the arm 10 can be readily returned to normal position and retained by a new bolt 13.

In Figs. 3 and 4, the arm 10 is jointed to a rod 17 on which is'fitted a spring 18 retained by a collar 19. The spring 18 bears at its one end against the boss 12 on the machine .frame 11. The operation of this arrangement is obvious from the drawings, the spring 18 automatically returning the arm 10 to'normal position after removal of the obstruction 14.

Figs. 5 and 6 illustrate a single toggle press holding a rod 20 between the matrices 2 and 3, the end of the rod 20 being operated on by a lateral press tool 21. In this case,- the journal 5 of the upper toggle link 4 is eccentrically mounted in the eccentric member 8, which may be centrally mounted in the machine frame. The arm 10 is carried by the eccentric member 8.

Figs. 6 and 7 show a mutiple toggle press in which the journals 5 of the upper toggle links 4 are mounted eccentrically in eccentrics 8 having the arms 10. In this case the two arms 10 can be directly connected together by the fragile bolt 13. When the bolt 13 fractures, the parts will assume the position shown in Fig. 8. Although as illustrated in Fig. 8, the obstruction may occur at one side only of the matrices 2 and 3, causing tilting of the parts and greater stress on one pair of toggles than on .the other pair, the operation of the safety device immediately relieves the stress on both toggles, so that excessive stress on the one side only is obviated.

Instead of mounting the crankshaft or its equivalent eccentrically in relation to the axially mounted eccentric, the arrangement may be reversed by mounting the crankshaft or its equivalent centrally on an eccentrically mounted part of the machine connected with the arm 10 or its equivalent.

The same effect can also be attained when the arrangement described and illustrated is applied to the lower operative parts of a press or the like.

Claims:

1. A safety device for reciprocating machines comprising means for transmitting the thrust to a rotatable member so as to tend to cause rotation of the member and means comprising a stationary member for arresting the rotatable member until the turning moment exceeds a given amount.

2. A safety device for reciprocating machines comprising an eccentric mounting for the journal of the reciprocating member and means comprising a stationary member for arrestlng eccentric motion of said ournal until the turning moment exceeds a given amount.

3. A safety device for reciprocating machines comprising an eccentric carried by the crankshaft of the machine, a journal for said eccentric, an arm projecting from said eccentric and means comprising a stationary member for preventing rotation of said arm until the turning moment exceeds a given amount.

4. A safety device according to claim 1 in whichthe arm is retained by a fragile member attached to said stationary member.

5. A safety device for multiple toggle presses comprising an eccentric carried by the crank journal of each pair of toggles, journals for said eccentrics, arms extending from said eccentrics and means for securely connecting said arms together and for releasing them from each other when the turning moment on the arms exceeds a given amount.

FERDINAND J OHN. 

